合成路线1

The compound can be obtained in a multistep synthesis as outlined in Scheme 18923701a. The cyclization of ethyl 3-amino-4-methylpent-2-enoate and 4-(ethoxycarbonyl)-5-(4-fluorophenyl)-2-methylpent-4-en-3-one (II) in a conventional dihydropyridine synthesis gives the dihydropyridine (III), which is oxidized to the symmetric penta-substituted pyridine (IV). After selective monoreduction with Red-Al the pyridine alcohol (V) is methylated to (VI). The second ester group is converted to the aldehyde (VII) in a two-step reduction/oxidation procedure. trans-Selective Wittig-Horner reaction with diethyl 2-(cyclohexylamino)vinylphosphonate affords the alpha,beta-unsaturated aldehyde (VIII). The condensation of (VIII) with methyl acetoacetate and subsequent erythro-selective reduction with triethylborane and NaBH4 results in the racemic dihydroxyester (IX). The reaction of (IX) with (S)-(+)-phenylglycinol yields the two diastereomeric (S)-(+)-phenylglycinolamides which can be separated on a silical gel column. After hydrolysis of the phenylglycinolamide (X) the sodium salt of the (+)-enantiomer is obtained.